Metallic colloid and process of producing the same



Patented Jan. 6, i 1

UNITED STATES PATENT OFFICE rmz E. 315030, 01' SANTA BARBARA. GALIFOBNIA, ASSIGNOB 1'0 max 3'. ULL- mu, 0: SANTA BARBARA, CALIFORNIA memo comm .um PROCESS OF PRODUCING THE Io Drawing.

This invention relates to metallic colloids and to a moose of producing the same.

Metallic colloidal solutions, when prepared by electrical disintegration of-metallic wires under water or ot er solvent in accordance with the well-known Bredig or Svedberg methods, are unstable if the metal of the colloid is readil oxidized. For example, aqueous colloi al solutions of the readily oxidizable metals like lead, zinc, 11011, etc., are very unstable and decompose to oxides, hydroxides and carbonates through reaction with the water and air. The reaction products precipitate out of the colloidal solution. By preparing such metallic colloids in dilute gelatine or other protective dispersing agent, the life of the colloid is increased, for although oxidation occurs, the dispersmg agent keeps the products in colloidal solution. Even, however, with the use of dilute gelatine as a dispersing agent, the resulting metallic colloid will stand up for only a short period of time, for example, a one-half per cent solution of lead will stand up for only about two days.

An object of the resent invention is to provide an improve metallic colloid and process of producing the same which is adapted to resist oxidation for a considerable period of time and which is adapted to stand up or retain its colloidal form.

I have discovered that by the addition of aliphatic poly-hydroxy compounds to the solution of the dispersing agent at the time of reparation of the metallic colloid, the polyiiydroxy compounds will operate to inhibit oxidation of the metal in the colloid, with the result that the metallic colloid is stable and may be preserved for several weeks. As an example of aliphatic poly-hydrox compounds which have been found suita le for use in the process, glucose, fructose, lactose and the like, when added to gelatine solutions used for preparing the colloid, greatly increase the stability of the metallic colloid against oxidation. Partial results also may be obtained by the use of saccharide, although the eflect is much diminished. Apparentl the decomposition products of any aliphatic poly-hydroxy compound, whether Application fled October 12, 1928. Serial No. 141,242.

alcohols, aldehydes or ketones, which'decomposition products are formed by the electric arc, exert inhibitin efiects towards oxidation of metallic colloids. Glycerol, for examplle,hisl found to be effective poly-hydroxy a co 0 The present invention also may be employed as a means for producing metals with out the metals going into the colloidal state. For example, if a solution of mono or di saccharide is employed without the use of gelatine, a metallic colloid forms but does not stay dispersed, but sinks to the bottom of the receptacle. The saccharide in this case exerts its specific effect against oxidation but does not operate as a protective agent for dispersion.

The invention, together with various further objects and advantages thereof, will be understood from a description of a number of exam les of metallic colloids and processes of pro ucing them embodying the present invention. I have therefore hereafter set forth examples of the effect of certain saccharides and other poly-hydroxy alcohols upon the stability of a lead colloid, lead colloids being particularly readily oxidized and diflicult to maintain in colloidal form.

In the production of a lead colloid, a dilute gelatine solution is first formed, for example by dissolving four grams of commercial gelatine in a liter of water. For the best results,

the pH ofthe solution is adjusted to 7.5

(colorometrically) To said solution is then added an aliphatic poly-hydroxy compound, for example, ten grams of either glucose, fructose, sucrose or glycerol. The solution is then subjected to a high fre uency oscillatory are between the electrodes 0 lead for a period of time, depending upon the concentration of thedesired metallic colloid. The apparatus is preferably employed in the usual Bredig arrangement. The current is 'referably adjusted so that the arc does not ame, but emits a yellow light. Black colloidal solutions of lead are formed. A suitable solution can be obtained in approximately five minutes time. Very dilute solutions of the colloid, such as contain less than .05 per cent lead, will remain stable due to the presence of a polyhydroxy compound for a period of time in excess of the time which the ordinary colloid will remain'stable.

Without the employment of the inhibiting agent of the present invention, a lead colloidal solution containing slightly less than .05 per cent lead was found to be entirely decomposed in three hours, no trace of black color remaining, while similar metallic colloids produced by glucose, fructose, and glycerol solutions, respectively, were still entirely black except for a slight narrow White hand at the top of the solution. A metallic colloid prepared from a sucrose solution will, at the end of three hours, be only half'decomposed. Other poly-hydroxy compounds, such as lactose or mannose, act similarly to sucrose, although dextrin is even less efficient. Metallic colloids prepared by the use of dextrose, fructose and glycerol solutions containing less than .05 per cent lead are only half oxidized at the end of twelve hours, and several days are required before the black color disappears and the white product of oxidation is formed.

Another example of a process embodying the present invention or metallic colloid produced thereby is as follows: Anaqueous solution containing .4 per cent gelatine and .5 per cent glucose is adjusted until its pH is between 7 and 8. If its pH is left between 5 and 7 lower yields will be obtained. The solution is then cooled such as by packing in ice, and subjected to a high frequency oscillatory are, using lead electrodes for one and one-half hours. Preferably the solution is stirred continuously and maintained at a temperature below 30 C., throughout the process. The are is preferably adjusted so that no flaming occurs. Optimum results are obtained when the gap between the electrodes 'is less than a millimeter.

At the end of the reaction, the solution is preferably centrifuged to separate the larger sized particles therefrom. Some oxide and carbonate will thus be settled. The solution thus prepared will contain between .3 and .8 per cent of lead in colloidal form. The solution may be bottled without special precautions and will remain stable for a number of weeks. The product may be sealed in tubes and heated to C., without affecting its stability. It may also be heated to boiling, which, however, will reduce its stability to only a few days. Deliberate attempt to break down the metallic colloid thus formed required the use of a constant stream of air for two days to completely oxidize one hundred cubic centimeter sample containing .5 per cent lead.

The practice of adding calcium salts to the gelatine, recommended in ordinary directions for the preparation of metallic colloids, is preferably avoided when poly-hydroxy compounds are employed as the colloid has a tendency to jell ou It is understood that the invention is not necessarily? confined to the production of lead colloids, as other metallic colloids can be prepared" in identical manner, and the invention has a wide application and relates generally to the broad field of metallic colloids. As an example of a particular use of the invention without limiting the invention thereto, the lead metallic colloidal solution prepared finds service as a cancer cure, and the present invention permits a suitable product to be prepared for thispurpose.

While the particular process herein described is well adapted to accomplish the objects of the present invention, it is understood the invention includes all such modifications and changes as come Within the scglpe of the appended claims.

claim:

1. A process of producing a metallic colloid comprising, distintegrating a metal in an aqueous solution of a saccharide and a protective dispersing agent.

2. A process of producing a lead colloid comprising electrically dismtegrating lead by forming an are between lead electrodes submerged in a solution of gelatine, the solution containing glucose.

3. A process of producing a metallic colloid comprising forming an are between metal electrodes submerged in a solution of protective colloid, the solution also containing a saccharide.

4. A process of producing a, metallic colloid for medical purposes comprising, disintegrating a metal in an aqueous solution of gelatin and an aliphatic poly-hydroxy com pound capable of retarding oxidation of the metal, said compound having substantially no reducing action.

5. A method of producing a metallic colloid for medical purposes, comprising forming an aqueous solution of gelatin and an aliphatic poly-hydroxy compound capable of retarding oxidation of dispersed metal, electricall disintegrating .a metal in said solution w iile maintaining said solution at a temill) llll

perature below 30 degrees C., and then removing coarse particles from the colloidal suspension thus formed.

6. A method of producing a metallic colloid for medical purposes, comprising forming an aqueous solution of gelatin and an aliphatic poly-hydroxy compound capable of retarding oxidation of dispersed metal, adjusting the pH of the solution to between 7 and 8, and electrically disintegrating a metal in said solution while maintaining said solution at a temperature below 30 degrees C.

7. A method ofproducing a lead colloid for medical purposes, comprising forming an aqueous solution of gelatin and an aliphatic poly-hydroxy compound capable of retardin oxidation of dispersed metal, adj usting 5w pH of the solution to between 7 and 8, and forming an are between lead electrodes submerged in said solution while maintaining the solution at a temperature below 30 degrees C.

Signed at Santa Barbara, Calif., this 23rd day of September, 1926.

FRITZ E. BISCHOFF. 

